Brazil's largest bank, Itau-Unibanco, has denied it is in talks to buy Citigroup's (C) stake in Mexican bank Banamex.

"Itau Unibanco is not negotiating any stake in Banamex's capital," the bank said in a statement late Wednesday.

Last week, Itau-Unibanco Chief Executive Roberto Setubal said his bank is looking at possible acquisitions elsewhere in Latin America, especially Mexico.

"We have a plan for overseas expansion and we will give careful consideration to opportunities as they arise," Setubal said. "If an important banking institution in Mexico comes up for sale, we will give that opportunity very careful study."

Itau-Unibanco was formed late last year by the merger of Itau (ITU), at that time Brazil's third largest bank, and Unibanco (UBB), at that time the country's fourth largest bank. The new merged bank is Brazil's largest financial institution. Itau and Unibanco shares still trade separately, but will be unified into a single new share on March 31.

People familiar with the situation said Citigroup executives have weighed the possibility of selling the Mexican holding, Grupo Financiero Banamex, according to a report in The Wall Street Journal. Investment bankers estimate Banamex could be worth at least $9 billion, according to the report.

"Citi has no intention of selling Banamex," Citigroup spokesman Jon Diat told The Wall Street Journal.

-By Rogerio Jelmayer, Dow Jones Newswires; 5511-2847-4521; rogerio.jelmayer@dowjones.com